\begin{tikzpicture}
    \tkzDefPoints{-1.5/0/A, 1.5/0/C, 0/-1/B, 0/1/D, 0/0/O}

    \tkzDrawPolygon(A,B,C,D)
    \tkzDrawSegments(A,C  B,D)
    \tkzLabelPoints[left](A)
    \tkzLabelPoints[below](B)
    \tkzLabelPoints[right](C)
    \tkzLabelPoints[above](D)
    \tkzLabelPoints[below left](O)
\end{tikzpicture}

